1. Field of the Invention
The present invention relates generally to mechanical and civil engineering, and in particular, to a method, apparatus, and article of manufacture for determining whether a construction can change its structure or not.
2. Description of the Related Art
In mechanical and civil engineering, determinations are often made regarding whether a structure is stable or not. To make such a determination, one needs to identify all of the structures in a construction that are fixed and those that are not fixed. In the past, to determine whether an entire construction was stable, the total number of construction/element nodes in a construction were counted and based on such a count, a determination was made. Further, some prior art systems attempted to experiment with a construction by pushing the construction to determine whether the construction moves (i.e., to determine its stability). Such prior art problems may be better understood with a brief explanation of computer drawing approaches in the construction industry.
In mechanical and civil engineering, there is a well-known problem referred to as DOF (degree of freedom). The problem consists of finding whether the construction can change its structure or not. In civil engineering a construction may be a bridge, a building skeleton, an antenna, etc. In mechanical engineering the construction may be machine elements such as excavators, car parts, etc. The DOF is one number that says what the possible moves of the construction are. In two dimensions (2D), the DOF can be a maximum of three. The three possible moves are: (1) an X direction move; (2) a Y direction move; and (3) a rotation. All of these three possible moves are present when the DOF equals three.
If the DOF is two there are only two possible moves present. If the DOF equals one it's just one possible move. The DOF may be also less than zero. A DOF value that is less than zero means that construction is over constrained.
A construction consists of components, joints of various types and supports that connect the construction to the frame. The problem is determining whether such a construction is stable or not using the DOF. As described above, in the prior art, attempts are made to move a construction and based on such movement, the DOF of the whole construction may be counted. However, the exact DOF for each construction element is not determined.